Tuesday, 21 November 2017

Simple Theremin

A recent request that caught my eye, a fairly simple theremin project. I've always found these to be neat with tons of possibilities when combined with other effects. The project was posted over on Instructables.




Original without Regulator


With Regulator

18 comments:

  1. Would it make sense to integrate a 78L05 somewhere in the top left (maybe by adding an extra cut to the left of the 5k1 resistor) so one could run it from a 9v supply or battery?

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    Replies
    1. I guess you can give a try is easy and you can use standard 9v.
      can I use LF412, TL082, TL072, TLC2272, TLV2372 instead MCP602?

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    2. I can make another layout with a regulator, shouldn't be too difficult to add. I'll do it tonight.

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    3. did you do the layout with the regulator yet? I would love to try that thing :P

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  2. Tlc2262 or tlc2272 are closest as they are both rail to rail like mcp602

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  3. first that crossed my mind was Jimmy Page :)

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  4. Just when I thought this site couldn't possibly get more awesome.
    Thanks so much Zach and all the other layout posters, you make this world go round !

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  5. I believe the layout won't work. The 4093 will need supply voltage at pin 14. This is not in the instructables schematic, but it's noted in the original from theremin world (http://www.thereminworld.com/pics/schematics/simple.jpg). Also, the photos at instructables show the supply connected to pin 14.

    May be worth noting that not terminating the unused schmitt triggers and the unused opamp will lead to problems. The opamp type won't matter, since the theremin world's schematic uses 4077 for amplifying the output. So in essence, a single opamp (like TL071 or LM741) would be a better choice here.

    The supply voltage of 9V vs. 5V will have different hysterisis voltage, but i'm fairly certain this circuit could be run with 9V stright off as the maximum rating for 4093 is 20V.
    +m

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    1. Cheers Miro. I thought that was odd pin 14 didn't have supply voltage. I'll take a look at the link you posted to where the schematic actually came from and make ththe changes.

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    2. 4077, or at least just using one gate of it, is an overkill for the amplifier part. I'd still go for 071/741.
      +m

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  6. I've recently delved into theremins and I really like the idea of having some on here, but frankly this doesn't sound great. If I have some time in the near future, I might try to lay out the Minimum Theremin from Harrison Instruments on a vero board.

    http://harrisoninstruments.com/101/101_schematic.html

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    Replies
    1. Hi Ryan, I would like to build a theremin too.
      Did you see this stripboard for Harrison's theremin?
      http://www.diystompboxes.com/smfforum/index.php?topic=102807.0

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  7. NOT verified. I just gave it a whirl. The regulator version that is. It gets white hot in seconds . I triple checkd everything . Please recheck layout. Thanks

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  8. Hello, I built this circuit with the regulator exactly as shown and I am getting 0 output. I quickly noticed that the regulator output (O) is not 5V, but much closer to 9VDC. I guess I would figure if the 78L05 were to fail, it would fail open, but I'm not 100% sure.

    I took voltage measurements throughout and with ~9V inputted to each IC I got:
    CD4093
    Pin 1 = 8.46V
    Pin 2 = 4.1V
    Pin 3 = 4.09V
    Pin 4 = 3.81V
    Pin 5 = 8.55V
    Pin 6 = 3.81V

    MCP602
    Pin 1 = 0.012V
    Pins 2&3 = 2.00V

    I also measured 4.08VDC on the antenna. Seeing basically 0V on the output of the MCP602 (pin 1) makes sense as to why I'm not getting anything to the output, but the fact that the regulator is not producing 5V concerns me. Is this my main trouble or should I investigate elsewhere? Thank you.

    ReplyDelete
  9. Hello, I built this circuit with the regulator exactly as shown and I am getting 0 output. I quickly noticed that the regulator output (O) is not 5V, but much closer to 9VDC. I guess I would figure if the 78L05 were to fail, it would fail open, but I'm not 100% sure.

    I took voltage measurements throughout and with ~9V inputted to each IC I got:
    CD4093
    Pin 1 = 8.46V
    Pin 2 = 4.1V
    Pin 3 = 4.09V
    Pin 4 = 3.81V
    Pin 5 = 8.55V
    Pin 6 = 3.81V

    MCP602
    Pin 1 = 0.012V
    Pins 2&3 = 2.00V

    I also measured 4.08VDC on the antenna. Seeing basically 0V on the output of the MCP602 (pin 1) makes sense as to why I'm not getting anything to the output, but the fact that the regulator is not producing 5V concerns me. Is this my main trouble or should I investigate elsewhere? Thank you.

    ReplyDelete
  10. Not sure weather to waste time building this or not, anyone actually built it and had a good result?

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